Girder



H. G. TREGLLLUS..

GIRDER.

APPuc/urmn FILED Amzs. |919.

HAROLD G. TREGILLUS, 0F BARRINGTON, ILLINOIS.

GEBDER.

esservi.

Application filed April 28, 1919.

To all whom it may concern.'

Be it known that I, HAROLD G. TREGILLUS,

a subject of the King of Great Britain, and

a resident of Barrington, in the county of Cook and State of Illinois, have invented .certain new and useful Improvements in Girders, of which the following is a speciication. Y

My invention relates to girder, rafter or truss structures for supporting roofs, can opies and other loads, and for use in bridges and similar structures. Structures of this class usually comprise an arch member, a

chord member and intervening connecting f and strengthening members.

The arrangement must be such that the arch will retain its proper curvature even though the load thereon is irregularly applied. Unless this is accomplished, an arch, supported at its ends upon abutments and loaded only on one side of its center, will defleet downward under the load, while the portion not so heavily loaded will rise above the original line of curvature.

The object of my 1nvent1on 1s to produ-ce a girder that is economical, rigidl and applicable to a variety of purposes. This I accomplish by a construction requiring only tension members for adequately maintaining the curvature of the arch under any irregular or eccentric loading.v In accordance with m invention tension members in the form o wires, rods or other material connect the arch abutments or other rigid supports with the arch at such points that under unequal load distribution on the arch the tension members will prevent rising of the arch at certain points, which rising would otherwise result if the load vwere unbalanced. The tension members of my im.- proved construction in effect serve the same purpose as balance loads which might be placed on the arch at points where the arch would tend to rise owing to the unbalanced llad. i

The preferred form of my invention comprises an arch member, abutment members therefor and the tension members extending `between the abutment members andthe arch. The structure can be of wood, metal- ;Specoation of Letters Patent.

Patented Feb. 1o, 1920.

Serial No. 293,160.

or combinationI of wood and metal, or the structure after being built up of metal can be embedded in concrete, the tension members and other members of the metal struc.

ture then serving as reinforcement for the concrete.

The various features of my invention ar clearly illustrated on the accompanying drawing, in which- Figure 1 is a side elevational View of my improved structure.

Fig. 2 is an enlarged vertical-sectional view of one end of the girder structure.

' Fig. 3 is an enlarged view of a section of the arch showing the manner of connection of the tension members therewith.

Fig. iis a sectional view on plane lf-4 of Fig. 3.

Fig. F ig. 2, and- Fig. 6 is a diagrammatic illustration of the operation of my invention.

The structure shown comprises the arch part 10, the supporting blocks 11A for the arch ends, the chord tension member 12 and the tension members 13 intervening between the chord member and the arch. In the structure shown the'arch is built up of *layers of wood in the, form of boards secured to each other by suitable means such as nails,4

and this arch seats at its ends in the recesses 14 formed in the ,end blocks 11, the arch and blocks being rigidly secured together by means of strap bolts 15 receiving the blocks and extending upwardly alongside of' the arch ends to receive washer plates 16 which are clamped against the arch top by the nuts 17. The chord member 12 may be in the form of a metal bar and extends longitudinally'. through the end blocks 11 and receives the nuts 18.. The blocks 11 may be of wood or metal as desired.

The tension members 13 may be in the form of wires or rods and connect between the end blocks 11 and lthe` arch at predetermined points. Fig. 2 clearly shows the 5 is a sectional view on plane 5-5 of manner of anchoring the ends of the ten- 1 sion members,

with thelr ends secured in suitable manner 20 in the inner `ends of the blocks and caps 2l at the corners around which the tension members are bent. Figs. 3 and 4 show a simple manner of connecting the tension members to the arch by means of eye-bolts 22 extending through the arch and through which the tension members are threaded.

In the structure above described only the arch itself is under compression when the structure is under load, thechord member 12 and intervening members 13 being only under tension. The chord member prevents spreading of the end blocks and the tension members prevent distortion of the arch and maintain its curvature under all load conditions.

F ig. 6 clearly illustrates the purpose and operation of the tension members. aY represents the arch at its normal curvature and supported by abutment members represented by the arrows Z) and c. Suppose now that a load represented by the arrow d isapplied near one end of the arch, the tendency will be for the arch to flatten at this point and bulge at some other point, it being impossible for the arch t0 flatten at one point Without bulging at some other point. 4

My invention is based on the principle that if bulging is prevented at one place then flattening will `be prevented at some other place where a load is applied. In Fig. 6 the dotted line shows the flattening and bulging oi' the arch if no meansv were provided for preventing this distortion. This distortion is prevented in my improved construction b the tension members. In Fig. 6 I have s iovvn tvvo such tension members e and f leading from the point g'respectively to the end abutments b and c. Under edect of the Weight al the arch will tend t'o bulge at the point g but the tension rods applied at this point vvill prevent this bulging and therefore flattening of the arch i atI the point of a plication of the load [Z will be prevented.' ny number'of such tension members may be provided in a girder structure and thus bulging at any point will be prevented'during the application of a load.l These tension members when considered with the chord member 7L would in eil'ect form a Bollman truss inverted and with posts omitted. When the tension members are stressed, the member ,t would ordinarily be in compression, but the loading which produces stress in the tension members, also tends to spread the arch and thus nulliiies the compression which would otherwise be in the member h, leaving a net result of tension. While the Bollman truss is the premacys/1f.

i'erred type tor the girder described, other types may be used to suit conditions, the basic principle being that the inverted truss is for the purpose of additionally loading the arch.

rlhe tie. members 13 in the form of rods or Wires may each have separate connection with the arch, or as shown in Figs. 3 and l pairs of such members 'may be formed by single lengths of Wire or other stoel( extend-- ing from one abutment blocl; through an eye-bolt and to the other abutment block. Also instead of having the structure partly ot Wood and partly ot metal, it could be constructed entirely of metalor entirely of Wood.l

The girder of my invention is simple and strong and economical of labor and materials.` It is of light Weight and can therefore be easily handled. ltl can be readily assem bled either in the shop or at the place of use.

Having described my invention, 'what l claim and desire to secure by Letters Patent is:

1. A truss structure comprising an arch, abutments for the arch ends and a plurality of tension members connecting each of said abutments with said arch members at various points throughout its length.

2. A truss structure comprising an arch, a chord, and web members, said web members forming a plurality of triangles having in common the entire chord for a base, and the arch joining the apexes of the said triangles.

3. A structure of the class described comprising an arch member, positive anchoring means, and tension means operatively connecting one point lof said anchoring means with said arch member at various points throughout its length.

4t. The combination of an arch and an inverted truss so disposed that the compression chord of the inverted truss becomes the tension chord ot the arch, the arch being operatively connected at various points throuehont its length to the inverted truss.

5. truss structure comprising an arch and a plurality of members radiating from one end of thearch and forming chords for sections of the arch.

t3. The combination with an arch, of a plu'n rality of members radiating from one end of the-arch and at their other ends connected with the arch at various points thereof.

7. An arch structure comprising an arch, and a plurality of tension members extending from each end of the arch and connected therewith at intermediate points.

8. A structure of the class described consisting of an arch member, and tension members arranged in pairs and connected to the ends of the arch member in common to intermediate points on said arch member.

titi

9. In a truss structure, the combination of an elastic arch member, ahutments under the ends thereof, said arch member alone supporting loads and transmitting the Weights thereof to said abutments, said arch member unless restrained tending to distort nnd'bulge under irregular loading, and restraining members anchored independently or' seid arch member and connected therewith to restrain such distorting or bulging 10 and to maintain the arch curvature thereof.

n Witness whereof, I hereunto subscribe my name this 24th day of April, A. D.,

HAROLD G. TREGJLLUS.l 

